This application claims the priority of German Patent Document 199 293 31.7, filed Jun. 26, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a vehicle communications system having a databus to which at least one front end unit with user-interface framework unit and one terminal which can be operated by the user are connected, and at least one application, also referred to below as functionality, which is implemented in the system and can be executed with the participation of the front end unit and of the terminals.
In modern motor vehicles, especially cars, numerous functionalities are implemented which are executed in the dialogue with the system user with the participation of respectively associated front end units which include associated user interfaces. These functionalities are particularly numerous telematics applications such as are specified, for example, in the German Laid-Open Application DE 196 25 002 A1.
In order to be best able to fulfill the resulting requirements, in recent times consideration has increasingly been given to using what are referred to as distributed systems, in particular systems which are based on object-oriented component models. In general electronic data processing, which have relatively high computing capacities in comparison to vehicle applications, techniques for supporting such distributed component systems are already customary, for example CORBA (Common Object Request Broker Architecture) and DCOM (Distributed Component Object Model). However, these techniques cannot be scaled down satisfactorily to small embedded units. In addition, DCOM is not presently available for the Windows CE operating system. For vehicle-end concepts for distributed systems, reference should be made, for example, to the periodical article by K. J. Neumann et al., Ein aufkommender Standard fxc3xcr verteilte Systeme im Kfz, atp 4/98, page 22, and the older German Patent Application 199 09 157.9 together with the literature cited there.
The present invention is addressed to providing a solution to the type of vehicle communications system of the type mentioned at the beginning, which permits, with an unacceptable amount of computing for vehicle applications, a mechanism for implementing distributed applications which are to be carried out using databus networks which are customary in vehicles, and in which the application can be kept as independent as possible of the type of bus system used.
The invention solves this problem by providing a vehicle communications system having a provision for the respective implemented functionality to be split into a part with user-interface ends and into a part with the functional components. At least the user-interface end part is part of a front end unit. The functional component part is also located in the same front end unit or else in another front end unit or in a multi-purpose platform unit which is also connected to the databus. The user-interface end part is connected to the user-interface framework unit in the respective front end unit, while the functional component part is correspondingly connected to an associated application framework unit in a communications connection. This system design constitutes a mechanism for the implementation of distributed functionalities to be executed, in particular also with respect to the subfunctions to be executed in that respect, such as display, operator control and interaction with other applications modules, with an amount of computing which is acceptable for vehicle applications.
In a further development of the invention, the respective functional component part is assigned a virtual terminal unit for communicating with the respective terminal which can be operated by the user takes place through the databus, and which contains the bus-specific implementation information required for this purpose. As a result, the functional components can be kept essentially independent of the type of databus system respectively used so that they do not necessarily need to be implemented each time another bus type is used.
In one aspect of the system, the functional component part is not located in the same unit as the user-interface end part but rather in another unit which is connected to the databus. The communication between the two parts is then carried out in the form of proxy-stub communication via the databus. With this system configuration, the user-interface ends do not need any knowledge of the distributed system environment currently present but rather they access the assigned proxy components which implement the necessary network operations. In the other unit, i.e. a further front end unit or a multi-purpose platform unit which is preferably provided centrally for a plurality of front end units, the respective stub component functions as a client of the functional components and communicates with the associated proxy component of the front end unit first mentioned. Because the entire network code is located in the proxy components and the stub components, any application-specific code can be kept completely independent of the databus network on which the system is based, without being involved in the networking, which simplifies its encoding and maintenance.